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2.2 Water demand and water use in the domesticand industrial sectors – An overviewULRICH SCHEELE & SIMONE MALZ

SUMMARY: Water is a critical and essential resource. World-wide the provision of new water services is outpacing population growth. Today 1.2 billion people have no access to safe drinking water and in spite of substantial progress, another 2.4 billion people have no access to adequate sanitation. The universally accepted goal to accomplish and to improve sustainable development can only be achieved by an integrated resource management strategy. The main reason for water crisis is population growth, particularly in developing countries. While for most people in Europe and other industrial countries, access to clean water in abundant quantity is taken for granted, in developing countries the growing water demand of the private household sector but espe-cially of the industrial and agricultural sectors leads to severe pressures on water resources. A balanced water supply and water demand management is a precondition for any water policy strategy. It requires a better understanding of those factors which influence the structure and future development of water demand.This article focuses on water withdrawals and water use of the private household and the industrial sector. It indicates that the water crisis is not a problem of water availability on a global scale but represents a regional problem.

Problem definition

A missing or insufficient management of water resourcesis regarded as one of the main constraints of sustainableeconomic and social development in the long run in manyregions of the world.

Water shortage is a common and prevalent issue on thepolitical agenda of different countries. The water relatedproblems will however be intensified by an ongoingpollution and excessive use of the available water resources.

The pressure on the available water resources stemsfrom the demand for drinking water but is also a result ofthe growing claims on the resources through the industrialand the agricultural sectors. There is the fear, that in thefuture political and even military conflicts around scarcewater resources will increase, since about 60 percent of thewater resources world-wide are shared by at least twocountries.

While the world population during the last five decadesdoubled, the water use world-wide has quadrupled.Although two thirds of the Earth’s surface consists of water,only a small fraction of these resources is directly utilisablefor human purposes.

A world-wide water crisis doesn’t necessarily mean anoverall water shortage compared to the water demand butthe problems arise from an uneven regional distribution ofwater resources. Especially the developing countries haveno or only insufficient financial, institutional, personal andtechnical resources, necessary to build up a functional watersupply and waste water sanitation system.

The figures are alarming: according to the World WaterDevelopment Report of the United Nations today about 1.2billion people have no access to an adequate water supplyand about 2.4 billion people world-wide have no access toa sewage and sanitation system at all. In the developing

countries, water related diseases count to the most frequentcauses of death. It is assumed that in average between10,000 to 20,000 children per day die as a directconsequence of the insufficient sanitary conditions in theirhomelands.

Under the prevailing basic conditions the problems willget worse and it will require enormous political andfinancial efforts in order to reach a trend reversal or at leasta stabilisation of the present situation.

The Johannesburg Summit on Sustainable Develop-ment describes the development of water supply as thebiggest challenge of the 21st century and for the first timedetermines very ambitious goals: so the number of peoplehaving no access to sufficient water and waste waterservices should be halved till the year 2015 (UNITED NATIONS

2004).Any serious solution of the world water crisis will not

only consist of additional financial resources transferred tothe developing countries but in the first place will have tofind new ways to balance regional water supply and waterdemand. In order to implement special water demandmanagement strategies there is a need for sufficientinformation about the structure of the current water useand the future development of different user categories.

The following chapters give a short overview of thedomestic and the industrial water use and it considers themethodology and the results of water demand forecastingapproaches.

Definitions and delimitationsWater is a renewable resource, therefore the term »waterconsumption« has to be defined more closely and analysedin a more differentiated way. First the difference betweenwater withdrawal and water consumption is relevant (Fig.2.2-1). Water withdrawals describe all quantities taken out

Ulrich.Scheele@uni-oldenburg.de

Scheele, U. & S. Malz (2007): Water demand and water use in the domestic and industrial sectors - An overview. In: Lozán, J. L., H. Grassl, P. Hupfer, L.Menzel & C.-D. Schönwiese. Global Change: Enough water for all? Wissenschaftliche Auswertungen, Hamburg. 384 S. Online: www.klima-warnsignale.uni-hamburg.de

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Fig. 2.3-1: Water with-drawal (abstraction) andwater consumption aspercentage of total renewablefreshwater resources inEurope (Source: EEA 1999,P 10) (= EUROPEAN ENVIRON-MENT AGENCY).

of groundwater and surface water reservoirs for human usesin a wider sense. Those water withdrawals which after theuse for domestic, industrial or agricultural purposes are notdirectly discharged back into the terrestrial hydrologicalsystem are marked as water consumption. In other words,consumption is the volume of water that is withdrawn, used,evaporated and not directly available for downstream users.Water quantities which are not consumed are dischargedback into the water cycle, however not necessarily at thesame point where they have been withdrawn. Comparablysmall withdrawals of water can lead to serious ecologicalproblems. An example is the desiccation of rivers due toexcessive withdrawals. It already suffices, if a minimumdischarge can not be secured in order to protect thefunctioning of an ecological system.

Water withdrawn from the water cycle serves differentpurposes. There is a distinction between the water use ofthe industry, the private households and the agriculturalsector. For further analyses this sub-structure is still not toospecific. Regarding the industrial sector, water use can beagain differentiated into drinking water, process water andwater for cooling purposes.

Process water is immediately used in the productionprocess for example as a transport medium or a solvent, orwater is directly incorporated in the product.

The water demand of the industry is characterised bydifferent water qualities depending on the specific uses.On the other hand, the water demand of the private house-hold sector is concentrated on a specific water quality, fixedby state agencies or by self regulation organisations in thedrinking water guidelines or directives.

On an international level, there is the problem of beingable to compare the data and figures related to water usedue to a lack of compatibility: Figures published inparticularly in those countries with a very poor andinsufficient water administration are often only based on

rough estimations. But also in a lot of industrial nations notall the industrial and agricultural users are connected to thepublic water supply network but use their own watersources to meet their demand. This water supply is notalways included in official water statistics.

The supply of drinking water to the population is inmost countries carried out by public water utilities. Thereare however large differences between the consideredwater-use categories: published data for drinking watersupply often contain water deliveries to private households;in other cases theses figures include also drinking watersupplies to small scale services and trade companies and tothe public sector (military, schools, hospitals, publicadministration).

In the meantime, in most Western European countriesthe connection rates of the private households to publicwater networks is almost 100%. On the global viewhowever, the majority of private households is still suppliedby water out of own water sources. Whereas in Germanyfor example the water use of private households is capturedby a flow measuring, even in some other countries of theEuropean Union there is no water metering in privatehouseholds.

The allocation of the cost of the water supply to thesingle dwellings is then based on criteria like the apartmentsize, number of residents or the rateable value oft the realestate. To conclude, the various organisational structuresand institutional arrangements make it difficult to draw in-ternational comparisons concerning the structure and thedevelopment of drinking water use in the private house-hold sector.

Water use of the private householdsApart from the very small portion of water which is forimmediate human consumption the main share of waterdemand of the private households refers to the production

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of »water services«. Water in households is mainly neededfor cleaning and washing, for personal hygiene, and fortoilet flushing (Table 2.2-1).

To satisfy the basic human needs like drinking, was-hing and cooking a minimum of about 5 litres water perday and person is estimated (GLEICK 1996). Of course thisvalue varies due to regional climatic conditions andindividual psychological features, the deviations in bothdirections are however comparatively low. The waterdemand increases, if an adequate quality of life and sanitaryconditions shall be achieved. The World Health Organi-sation (WHO) and the US Agency for InternationalDevelopment published an estimated water requirement ofabout 20 to 40 litres per capita and day and, while theEuropean Environmental Agency estimates a minimumrequirement of about 80 litres per capita and day.

Taking these minimum requirements into accountpresent studies and reports covering the world-wide watersupply show that half of the current world population cannot rely on water services which were already standard tothe old Romans and Greeks (WOLFF & GLEICK 2002).

Compared to the total amount of water withdrawn fromthe groundwater and surface water reservoirs, the wateruse of the private household sector is only of minorimportance, but there are large differences betweencountries and regions. The world-wide water demand ofprivate households grows due to an increase in worldpopulation and the ongoing processes of urbanisation inthe developing countries. On the other side, in the mostdeveloped countries domestic water demand varies stronglybut all together the situation is characterised by a stagnantdevelopment or in some cases by a real decrease of thewater use figures.

The water use of the private households is measuredby the volume of water which is withdrawn from the centralpublic water supply network. The specific water use figuresper day and capita are then calculated under theconsideration of the total population number within therespective regional or local supply area. Internationalcomparisons of water use figures have to take into accountthat in many countries only a part of the population isconnected to a public water supply network. Therefore, thestatistic figures published may be stated too low in thosecountries; on the other hand the specific water use rate maybe too high in those countries or regions where tourism isof significant importance (WIELAND 2003, p. 3).

Water use in households varies enormously betweendifferent regions: while around 20 litres per capita and dayare used in the rural arid regions in Africa, an US – Ameri-can has in average a water demand of almost 300 litres perday.

The average per capita water use within the memberstates of the EU is currently around 150 litres per day, but

even within this association of developed countries thefigures vary between 113 litres per capita and day inBelgium and 214 litres in Finland.

The specific water use value in the new accessioncountries of the EU is 105 litres per capita and day onaverage. This below-average value is mostly a combinedeffect of a lower standard of living and a higher rate of selfsufficiency. In Germany the specific water consumption in2004 was 127 litres per capita and day, about 20 litres lowerthan the water use in the year 1990, shortly afterreunification.

Table 2.2-1 represents the share of the water usecategories of the domestic sector in Germany. The data aremainly based on estimations since the water use inhouseholds is not differentiated between the individualcategories. Hence, international water use studies showcomparable results.

Industrial water use

About 20 per cent of the world-wide water withdrawn isused in the commercial and industrial sector. Thedifferences between different countries are considerable;the share of the industrial sector at the total water use isalmost 60% in the developed countries whereby the role ofthe agricultural sector as water consumer plays acomparatively minor role in these countries.

According to different scenarios, an increase of theindustrial water demand up to 1,170 km3 per annum till theyear 2025 is expected on the global level, this wouldcorrespond to a share of this sector at the total water use ofabout 24 per cent. The largest part of this projected increasein industrial water use will be realised in those developingcountries with high economic growth rates, and especiallyby those which heavily rely on resource – intensiveindustries. Water demand projections show a rise in wateruse for electricity generation especially in the African,Asian and Latin American countries.

In the European countries water use in the industry iscurrently around 10% in average, not taking into accountthe water withdrawn for cooling purposes in the electricitygeneration process. If the water quantities needed forcooling purposes or used in hydroelectric power stationsare included, then the share of the industrial sector at thetotal water withdrawals is up to 32% (see Table 2.2-2).

During the 1980s and the 1990s, the industrial wateruse considerably decreased in the most developedcountries. This development is to a great extent caused bynew production technologies with lower water input and ina broader sense a decoupling of economic growth andresource consumption. This can impressively be illustratedby the following examples: Before World War II the waterquantity needed for the production of one ton of steel was

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Boiling and drinking 3Personal hygiene 6Baden and showers 30Toilet flush 32Cleaning 3Washing the dishes 6Wäschewaschen 14Garden sprinkle 4Car laundry 2

Total 100

Table 2.2-1: Percentage composition of the private consumption(department of the environusement 2001, p. 34)

Source: EEA, Environmental assessment report of No 1:Sustainable water use in Europe, share 1: Sectoral Use of Water

Country Industrial Cooling waterwater consumption for power stations

(without cooling water) and water power(×106 m³) (%) (×106 m³) (%)

Belgium 210 3.0 5,149 73.4Denmark 82 9.0 0 0.0Germany 6,475 11.0 16,952 28.8Finland 1,111 33.2 1,690 50.5France 3,942 9.7 25,835 63.5Greece 136 2.7 91 1.8Großbritanien 848 7.0 1,721 14.2Ireland 250 20.6 277 22.8Italy 7,980 14.2 7,025 12.5Luxe castle 14 24.5 0 0.0Netherlands 507 4.0 11,028 87.0Austria 489 20.7 885 37.5Portugal 241 3.3 2,682 36.8Sweden 1,479 54.6 70 2.6Spain 1,647 4.6 4,915 13.9

Total 25,411 10.4 111,612 31.8Average value Average value

* water can be used repeatedly

Table 2.2-2: Share of the industry in the complete waterwithdrawal (EUROPEAN ENVIRONMENT AGENCY 1999).

about 60 to 100 tons, today with improved technologies thewater use has been reduced to less than 6 tons of water perone ton of steel. A further reduction of water use in thisbranch is due to a substitution of steel through aluminiumfor example in the automobile production (WOLF & GLEICK

2002, p 23; EUROPEAN ENVIRONMENTAL AGENCY 1999).This development is expressed in the literature by dif-

ferent ratios. The concept of »water productivity« is forexample a useful instrument to describe changes in theindustrial water use. This indicator relates the quantity ofgoods and services to the quantity of water necessary toproduce these goods. The quantity of produced industrialgoods and services can be measured in physical units(number of the products, weight etc.) or in monetary units(gross domestic product, gross added value).

The term »water use efficiency« describes anotherconcept and considers the potential of water savings in theindustrial sector. Efficiency is the ratio between theminimum of water needed for a certain kind of productionprocess and the quantity of water currently used in thisprocess. Every reduction in the current water use leads toan improvement of the efficiency measure in direction of1.0 (i.e. 100 per cent efficiency).

Although there is an improvement in the world-widewater productivity during the last decades, there are ofcourse some considerable differences between the coun-tries. This is a result of a very uneven access to new tech-nologies, the various degrees of economic structural chan-ges and the different emphasis of water – intensive bran-ches. But also dissimilar water costs as well as specificenvironmental policies may be of importance in thiscontext.

Water demand projections

Prerequisite for a long term sustainable management ofwater resources is a reliable estimation of future watersupply and water demand in a region or in any country.Since the 1960s there has been numerous global waterdemand projections, mainly based on the analysis and theextrapolation of historical water use figures.

GLEICK (2000) evaluates altogether 26 global waterdemand projections published since 1967 which deal withprojection periods between 20 years and half a century.

The results of his study are clear : The older studies arevery simple trend extrapolations of water use and operatewith ratios in the form of water use per person or per acrein the case of irrigation. More current studies use a largernumber of demand categories and distinguish betweendomestic, industrial and agricultural water demand and thewater needed to maintain ecological functions. Somestudies also take into account water losses in the supplynetwork as well as the potential effects of climate changeson water resources and water demand. The quality of theprojections is improving since more developed projectionmethods are applied, and a broader data base and expandedinformation processing capacities are available.

Today water demand projections are based on thescenario method. This is not a forecast or projection in thenarrower sense but a method to show possible futuredevelopments taking into account different circumstancesand assumptions about the development of the main factorsinfluencing water demand. Depending on those differentconditions and sets of relevant factors, several futureoutlines can be distinguished.

The World Water Commission for example describesthree scenarios to assess world-wide water supply and waterdemand till the year 2025. The »Business as usual«

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Fig. 2.2-2: Water use by states (UNITED NATIONS 2003, p.19).

scenarios describes the future water demand assuming thatthere is no change in the economic, social or politicalframework and relies therefore on the extrapolation ofrecent trends. The second scenario focuses on future waterdemand under the assumption that there is a decisiveimprovement in water use efficiency due to newtechnologies. The third scenario deals more with changinglife styles, values and consumer behaviour and describes apicture of a more sustainable society.

A comparison of the predicted results with the actualresults turned out the deficits of most forecast methods.The former projections have overestimated the currentwater use since they simply extrapolated historical trendswithout taking into account the changing economicconditions and the effects of new social, institutional orpolitical frameworks. The lower growth of the water useresulted from considerable but maybe not predictableimprovements in the water use efficiency. Of course waterdemand is also influenced by the very unfavourableeconomic developments in a lot of countries.

In the midst 1990s the actual water withdrawals wereworld-wide only half of those quantities predicted in thedemand forecasts 30 years ago. SHIKLOMANOV (2000)assumes that in the year 2025 there will be less global wateruse than he himself has calculated 1974 in a demandforecast for the year 2000.

From this point of view it appears to become obviousthat at least on the global scale there will probably be noproblems with the availability of water resources in aforeseeable future. To illustrate this assessment: even ifaccording to recent projections the world population shouldincrease to about 9.4 billion people in 2050 and if oneassumes an average per capita water use on the current(high) US level, a per capita water volume of 4,600 m³/year

would still be available (SCHMANDT 2003).Despite these good news at the global level there are

however regional imbalances between water supply andwater demand all over the world and there are clear signsthat these problems will increase in the future.

For the implementation of an effective watermanagement, regional water demand projections should beavailable which take into account all relevant factors andconditions influencing future water demand.

In the context of the UNESCO InternationalHydrological Programme IV a total of 26 regional waterdemand projections for so called »natural economicregions« were drawn up; these large scale regions arecharacterised by comparable economic and naturalconditions. Such regional studies are useful to determinethose areas which in future will be confronted with seriouswater problems due to an increase in water demand and/ora reduction of available water resources. The distinctionbetween »water stress« and »water scarcity« regions is ofrelevance for policy implementation. »Water stress« meansthat in certain regions only between 1,000 and 1,600 m³ ofwater are available per capita and year, in a water scarceregion the water availability is limited to only 1,000 m³ orless per capita and year.

Western European countries are altogether classifiedas water stress regions but according to recent demandstudies this situation would not deteriorate however. Mo-dern sewage treatment methods and water reuse techniqueswill probably reduce the future water demand in thedeveloped countries. Nonetheless, under »business asusual« assumptions, the number of people living in waterstressed regions will globally rise to about 3.4 billion world-wide until the year 2025, compared to 1995 this would bealmost a doubling♦